High performance microwave dielectric systems and methods

ABSTRACT

Loss tangents in microwave dielectric materials may be modified (increased and/or reduced), particularly at cryogenic temperatures, via application of external magnetic fields. Exemplary electrical devices, such as resonators, filters, amplifiers, mixers, and photonic detectors, configured with dielectric components having applied magnetic fields may achieve improvements in quality factor and/or modifications in loss tangent exceeding two orders of magnitude.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. Ser. No. 14/464,518 filed on Aug. 20, 2014, now U.S. Patent Application Publication No. 2016-0352314 entitled “HIGH PERFORMANCE MICROWAVE DIELECTRIC SYSTEMS AND METHODS”. U.S. Ser. No. 14/464,518 claims priority to, and the benefit of, U.S. Provisional Application Ser. No. 61/868,896 filed Aug. 22, 2013 entitled “HIGH PERFORMANCE MICROWAVE DIELECTRIC.” The entire contents of each of the foregoing applications is hereby incorporated by reference herein for all purposes.

FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

This invention was made with government support under grant number W911NF-11-1-0508 awarded by the Army Research Office. The Government has certain rights in the invention.

TECHNICAL FIELD

The present disclosure relates to dielectric materials, and in particular to reduction and/or modification of loss tangents in dielectric materials containing paramagnetic additives via application of an external magnetic input or signal.

BACKGROUND

Certain existing dielectric materials, for example dielectric materials suitable for microwave operation, and devices incorporating the same suffer from various shortcomings, for example excessive and/or temperature-varying loss tangents. Accordingly, improved dielectric materials and devices incorporating the same remain desirable.

SUMMARY

In an exemplary embodiment, a method for modifying the loss tangent in an electrical device comprises operating the electrical device having a dielectric component containing a paramagnetic additive. The operating subjects the dielectric component to electromagnetic radiation having a frequency of between 0.2 GHz and 120 GHz. The method further comprises applying a static magnetic field to the dielectric component to modify the loss tangent in the dielectric component.

In another exemplary embodiment, a method for varying the transfer function of an electrical device comprises operating the electrical device having a dielectric component containing a paramagnetic additive. The operating subjects the dielectric component to electromagnetic radiation having a frequency of at least 0.2 GHz. The method further comprises applying a magnetic field to the dielectric component to modify the transfer function of the electrical device.

In another exemplary embodiment, an electrical device configured with a reduced loss tangent comprises: an active electrical component comprising a dielectric material; and a magnetic field generation component configured to apply a static magnetic field to the dielectric material.

In yet another exemplary embodiment, a method for reducing loss in a dielectric material comprises: determining, for paramagnetic ions in the dielectric material, a preferential spin alignment; and applying, to the dielectric material, a static magnetic field to cause the paramagnetic ions to assume the preferential spin alignment.

In still another exemplary embodiment, a method for modifying loss in a dielectric material comprises: determining, for paramagnetic ions in the dielectric material, a resonant spin loss; and applying, to the dielectric material, a static magnetic field to attain a resonant condition for the paramagnetic ions and modify the loss tangent of the dielectric material.

The contents of this summary section are provided only as a simplified introduction to the disclosure, and are not intended to be used to limit the scope of the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

With reference to the following description and accompanying drawings:

FIG. 1A illustrates an exemplary system for characterizing microwave material and/or device properties over a range of temperatures and/or magnetic fields in accordance with various exemplary embodiments;

FIG. 1B illustrates unloaded Q factor and loss tangent of Ba(Zn_(1/3)Ta_(2/3))O₃ (BZT) doped with various impurities measured with a parallel plate resonator configuration at 4.2 K and no applied magnetic field in accordance with an exemplary embodiment;

FIG. 1C illustrates measured Q of Ni-doped ceramic BZT at 4.2 K as a function of static magnetic field measured using a dielectric resonator configuration in accordance with an exemplary embodiment;

FIG. 1D illustrates inferred loss tangent and absorbance of Ni-doped ceramic BZT at 4.2 K as a function of static magnetic field measured using a dielectric resonator configuration in accordance with an exemplary embodiment;

FIG. 1E illustrates loss tangents of Ni-doped ceramic BZT as a function of temperature in accordance with an exemplary embodiment;

FIG. 2A illustrates loss tangents of exemplary commercially available dielectric materials as a function of temperature in accordance with an exemplary embodiment;

FIG. 2B illustrates unloaded Q factor for exemplary Ba(Zn_(1/3)Nb_(2/3))O₃ dielectric materials of various dopings and at various temperatures, all as a function of static magnetic field in accordance with an exemplary embodiment;

FIG. 3A illustrates loss tangent for exemplary commercially available dielectric materials at 4.2 K as a function of static magnetic field in accordance with an exemplary embodiment;

FIG. 3B illustrates unloaded Q factor for exemplary commercially available dielectric materials at 4.2 K as a function of static magnetic field in accordance with an exemplary embodiment;

FIG. 3C illustrates unloaded Q factor for an exemplary commercially available dielectric material (D3500 (Ba(Zn_(1/3)Nb_(2/3))O₃+2Ba(Co_(1/3)Nb_(2/3))O₃) at 120 K as a function of static magnetic field in accordance with an exemplary embodiment;

FIG. 3D illustrates unloaded Q factor for an exemplary commercially available dielectric material (Co-doped Ba(Zn_(1/3)Nb_(2/3))O₃) under various static magnetic field and as a function of temperature in accordance with an exemplary embodiment;

FIG. 4A illustrates loss tangent for exemplary commercially available dielectric materials at 300 K as a function of static magnetic field in accordance with an exemplary embodiment;

FIG. 4B illustrates unloaded Q factor for exemplary commercially available dielectric materials at 300 K as a function of static magnetic field in accordance with an exemplary embodiment;

FIG. 5 illustrates a functional block diagram of an electrical device configured with a reduced loss tangent in accordance with various exemplary embodiments;

FIG. 6A illustrates a method for reducing the loss tangent of an electrical device in accordance with various exemplary embodiments; and

FIG. 6B illustrates a method for modifying the transfer function of an electrical device in accordance with various exemplary embodiments.

DETAILED DESCRIPTION

The following description is of various exemplary embodiments only, and is not intended to limit the scope, applicability or configuration of the present disclosure in any way. Rather, the following description is intended to provide a convenient illustration for implementing various embodiments including the best mode. As will become apparent, various changes may be made in the function and arrangement of the elements described in these embodiments without departing from principles of the present disclosure.

For the sake of brevity, conventional techniques for dielectric material fabrication, characterization, use, and the like, and/or devices, systems, and methods incorporating or based on the same, may not be described in detail herein. Furthermore, the connecting lines shown in various figures contained herein are intended to represent exemplary functional relationships and/or physical couplings between various elements. It should be noted that many alternative or additional functional relationships or physical connections may be present in a practical high performance microwave dielectric and/or electrical devices incorporating the same.

In accordance with principles of the present disclosure, performance of various electrical devices, for example resonators, filters, amplifiers, mixers, photonic detectors, and/or the like, may be improved and/or refined. For example, the quality factor of resonators, or performance of microwave filters, may be improved via use of dielectric resonators subjected to a magnetic field. Exemplary methods and systems may be applied both at low temperatures and with high magnetic fields, and at higher temperatures and with lower magnetic fields. Magnetic fields may be applied using a variety of methods for generation of such fields (for example, using permanent magnets or using electromagnets formed using electromagnetic circuits or devices).

In accordance with various exemplary embodiments, the loss tangent of microwave dielectrics may be reduced and/or modified via application of a magnetic field. In certain exemplary embodiments, the effect is prominent at low temperature. In certain exemplary embodiments, the effect is prominent at low temperature and when transition metals with unpaired d-electrons are utilized. The effect may also be seen at higher temperatures (i.e., up to and exceeding 300 K) and with other paramagnetic additives. Reducing and/or modifying the loss tangent of high dielectric constant dielectric materials is extremely desirable, particularly for microwave communication and radar systems where losses in dielectric resonators and/or filters limit the overall performance of the system.

Properties of certain dielectric materials, for example:

-   -   Ba(Mg_(1/3)Ta_(2/3))O₃     -   Ni- and Zr-alloyed Ba(Zn_(1/3)Ta_(2/3))O₃     -   Co-alloyed Ba(Zn_(1/3)Nb_(2/3))O₃     -   ZrTiO₄—ZnNb₂O₆     -   BaTi₄O₉—BaZn₂Ti₄O₁₁         and/or the like may be improved and/or optimized by adding         certain dopants and/or solid solution alloy agents, for example         Ni, Zr, Co, Mn, and Cu (sometimes referred to herein as         “additives”). Certain rare earth paramagnetic materials may also         be utilized as additives. These impurities can act as sintering         aids to enhance the manufacturability, crystal quality, and/or         density, and thus ultimately the quality factor Q. Additionally,         these impurities can be utilized to increase the dielectric         constant and/or adjust the temperature coefficient of resonance         frequency tr to a value close to or equal to zero.

However, these and other paramagnetic impurities can also have significant effects on the loss tangent of the material, and the effect may vary significantly across temperatures. Principles of the present disclosure demonstrate that the dominant loss process in exemplary microwave dielectrics containing paramagnetic transition metal additives at cryogenic temperatures is resonant spin excitations of unpaired d-electrons: (i) for small dopant concentrations (i.e., about 3% to about 8% mole fraction or less), within isolated transition metal atoms; and (ii) for higher dopant concentrations (i.e., typically greater than about 8% mole fraction), within exchange-coupled transition metal clusters.

Accordingly, in contrast to the shortcomings of prior devices and materials, application of principles of the present disclosure enables higher performance electronic devices, for example resonators, filters, and other microwave devices. Resonators and oscillators may be configured with higher quality factors and/or lower intensity and phase noise. Filters may be configured to achieve lower insertion loss, sharper skirts, and/or lower intensity and phase noise. Additionally, the transfer function of exemplary electronic devices configured in accordance with principles of the present disclosure, for example resonators, oscillators, filters, and/or the like, can be tuned by varying an applied magnetic field, for example by changing the position of a permanent magnet, or the current magnitude and/or direction of a magnetic coil. The applied magnetic field can modify the resonant spin loss properties and can create a preferential spin alignment in the dielectric material, reducing and/or modifying the loss tangent and/or other electromagnetic properties of the dielectric material.

With reference now to FIG. 1A, in accordance with various exemplary embodiments, exemplary microwave measurements to assess the loss tangent of certain dielectric materials may be performed in transmission utilizing a dielectric resonator (DR) technique. An exemplary system 100 for measurement is illustrated in FIG. 1A. In an exemplary embodiment, DR measurements may be made using rectangular resonators 105 of a suitable size, for example, 8.5 mm×6.5 mm×2 mm. The resonators may be loaded into a suitable cavity 110, for example a gold-plated copper cavity having dimensions of about 2 cm×0.6 cm×1.5 cm, and the cavity may be affixed to the end of a cryogenic dipping probe. For measurements without an applied external magnetic field, the probe may be inserted into a helium dewar or other suitable cooling device. For measurements including an applied external magnetic field, the probe may be inserted into a suitable cryostat 120 (for example, PPMS, Model 6000 from Quantum Design in San Diego, Calif., or the like). In a suitable cryostat, measurements at temperatures as low as about 2 Kelvin and under applied external magnetic fields as high as about 9 Tesla may be achieved.

A microwave vector network analyzer (VNA) 130, for example the Hewlett-Packard 8510C or similar, may be used to source transverse electromagnetic modes and then measure Si vector values. These values may be fit to a circle in the Smith chart to infer the Q factor. In various exemplary embodiments, the distance between the coupling loops and the sample material may be configured to be weakly coupled; in this manner, the unloaded Q may be determined at a precision within a few percent. Loss tangent values measured with the DR measurement technique align closely with values obtained when using superconducting parallel plate resonator (PPR) techniques, likely due to confinement of fields in the high dielectric constant materials and thus minimizing the radiation and near field losses. For the dielectric materials in question, chemical composition and trace amounts of impurities may be quantitatively characterized utilizing secondary ion mass spectroscopy (SIMS) and particle induced X-ray emission (PIXE).

Exemplary measurements via system 100 of loss tangent and unloaded Q factor for BZT doped with various impurities, as measured at 4.2 K and under no applied magnetic field, are illustrated in FIG. 1B. Exemplary measurements via system 100 of unloaded Q factor of Ni-doped BZT, measured at 4.2 K and across a range of applied magnetic fields, are illustrated in FIG. 1C. Inferred loss tangent and absorbance of the materials in FIG. 1C are illustrated in FIG. 1D. In FIG. 1D, the inset illustrates an expanded view at low magnetic field values, and arrows point at EPR resonant absorption peak maxima. Additionally, exemplary measurements via system 100 illustrating temperature dependence of microwave loss tangent from 4.2 K to 300 K are illustrated in FIG. 1E for BZT and for various materials in FIG. 2A.

Continuing to reference FIG. 1E, as the temperature of BZT falls from 300 K toward 4.2 K, the loss tangent initially decreases. However, as the temperature falls further, significant increases in loss tangent occur. The loss scales with the doping concentration of Ni. The temperature where the loss tangent starts to increase varies with the doping level: for 8% Ni, about 20 K; for 20⁰ Ni, about 60 K; and for 40% Ni, about 160K; as discussed in U.S. Provisional Patent Application 61/868,896, the foregoing percentages refer to the fraction of Ni on the Zn site, thus corresponding to a content of 0.53% for 8% Ni, 1.33% for 20% Ni, and 2.67% for 40°/o Ni. With momentary reference to FIG. 2A, corresponding temperatures are: for BaTi₄O₉—BaZn₂Ti₄O₁₁, about 10 K; for Ba(Zn_(1/3)Ta_(2/3))O₃, about 50 K; and for Ba(Zn_(1/3)Nb_(2/3))O₃, about 200 K.

PIXE and SIMS may be utilized to verify that the samples have transition metal ions, for example as illustrated in Table 1.

TABLE 1 ZrTiO₄—ZnNb₂O₆ BaTi₄O₉—BaZn₂Ti₄O₁₁ Ba(Zn_(1/3)Nb_(2/3))O₃ Ba(Zn_(1/3)Ta_(2/3))O₃ Impurity cm⁻³ Impurity cm⁻³ Impurity cm⁻³ Impurity cm⁻³ Cu 9.3 × 10¹⁹ Cu 9.1 × 10¹⁹ Co 3.2 × 10²¹ Ni 6.1 × 10²⁰ Mn 2.8 × 10¹⁹ Mn 5.4 × 10¹⁹ Mn 4.2 × 10¹⁹ Fe 9.6 × 10¹⁸ Fe 3.8 × 10¹⁸ Fe 4.6 × 10¹⁸ Co 7.3 × 10¹⁷ Co 6.5 × 10¹⁷ Cr 3.2 × 10¹⁷ Cr 2.7 × 10¹⁷

Materials with relatively high concentration of transition metal Ni and Co ions often have large microwave loss at cryogenic temperature, while materials that contain smaller and/or trace amounts of transition metal ions often have small microwave loss at similar temperatures. Accordingly, principles of the present disclosure indicate that the presence of “magnetic” additives, for example Ni, Co, Cu, Mn, and Fe, play the dominant role in the microwave loss mechanism in these exemplary dielectric materials at cryogenic temperatures.

Table 2 illustrates magnetic properties of BZT doped with a variety of Ni concentrations.

TABLE 2 From temperature-dependent low-field magnetic susceptibility From fitting Brillouin function measurements (characteristic of to magnetic-field-dependent all unpaired electrons) susceptibility measurements Ni Fraction Weiss (characteristic of clusters) concentration of Ni Average Ni μ_(eff) = g_(j){square root over (J(J + 1))} temperature J (measurement M_(s) (emu/cm³) (cm⁻³) on Zn site separation (Å) per Ni atom (μ_(B)) (K) temperature in K) {g_(j)J} 5.2 × 10¹⁹ 1% 27 3.11 0.5 0.65 (4.2)  0.9, {1.9}  4.1 × 10²⁰ 8% 13 2.97 1.4 1.5 (4.2)  7.7 {2.1} 1.0 × 10²¹ 20% 9.9 3.03 1.8 2 (10) 20 {2.2} 2.1 × 10²¹ 40% 7.9 2.96 3.3 3 (15) 40 {2.2} 3.1 × 10²¹ 60% 6.9 2.97 4.6 4 (20) 64 {2.4} 4.1 × 10²¹ 80% 6.2 2.94 6.4 10 (20)  87 {2.4}

Doped and undoped Ba(Zn_(1/3)Ta_(2/3))O₃ made in a lab and doped commercial material (for example, products 2900 and 8733 available from Trans Tech, Adamstown, Md.) demonstrate the variability of loss tangent associated with application of an external magnetic field disclosed herein. Additionally, the effect may also be demonstrated in other commercial ceramics including Ba(Zn_(1/3)Nb_(2/3))O₃+2Ba(Co_(1/3)Nb_(2/3))O₃ chemical composition-based material (for example, product 3500 available from Trans Tech, Adamstown, Md.).

This effect may be realized in various other high performance materials, especially at low temperatures and with materials that contain or are doped with transition metal elements with unpaired d-electrons. Table 3 presents certain commercially available high performance microwave dielectrics and their approximate composition:

TABLE 3 Lattice Composition Constant Sample (by PIXE)* Additives Major Phase structure (A) Substrate (A) D3500 Ba1 Zn0.1 Ba(Zn0.33Nb0.67)O3 perovskite 4.0935 LiF(4.026) or Nb0.55 Ge(5.675) Co0.23 O~3 D4300 Zr1 Ti1.80 Cu~0.035% ZrTiO4 orthorhombic a 4.7855 Si(5.43) Zn1.08 Ca (trace) b 5.4755 Nb0.31 O~7 c 5.0277 D8300 Ba1 Ti3.48 Ta~0.3% BaTi4O9 orthorhombic a 6.2940 LaAlO3(a = 3.79 Zn0.50 O~9 Rh~0.03% b c = 13.11) 14.5324 c 3.7972

The absorption process involves localized electron spin flips (i.e., electron paramagnetic resonance (EPR) transitions) of (i) individual ions when distances between ions preclude the formation of exchange-coupled spin clusters, and/or (ii) of exchange-coupled spin clusters when the distance between ions reaches a sufficiently small value to permit formation of exchange-coupled spin clusters (i.e., less than about 8 Angstroms for Ni²⁺ ions, less than about 7 Angstoms for Co²⁺ ions, etc.).

With reference now to FIG. 2B, principles of the present disclosure contemplate that, in various exemplary dielectric materials, unloaded Q factor often initially declines upon application of a small magnetic field (typically from about 0 T to a value of less than about 0.5 T, depending on material, and for many materials, less than about 0.2 T), and thereafter increases as the magnetic field increases. The initial drop in Q is due to electron paramagnetic resonance conditions, and the rise in Q is due to preferential spin orientation. Change in unloaded Q factor over a range of magnetic fields can be quite large. For example, for Ba(Zn_(1/3)Nb_(2/3))O₃ doped with Co to 20%, the difference in Q obtainable over the range 0 T to 4 T is more than one order of magnitude.

Skilled practitioners will appreciate that, as disclosed herein, loss in exemplary dielectric materials is highest during paramagnetic resonance conditions and is lowest at high magnetic fields (i.e., greater than about 0.5 T for operation at about 10 GHz). Paramagnetic resonance conditions generally occur at magnetic fields of less than 0.5 T for operation at about 10 GHz. Notably, the Zeeman energy separates the favored spin state in the B-field direction from the higher energy state that opposes it.

With reference now to FIGS. 3A, and 3B, principles of the present disclosure contemplate that the loss tangent and quality factor of components comprising various exemplary dielectric materials, when operated at cryogenic temperatures, may be modified via application of an external magnetic field. In various exemplary embodiments, the loss tangent of certain exemplary materials may be reduced by more than two orders of magnitude at 4.2 K via application of an 8 T external magnetic field. Accordingly, it is clear that microwave loss can be largely suppressed by aligning the spin via application of a sufficiently strong static magnetic field.

Turning now to FIGS. 3C and 3D, principles of the present disclosure contemplate that the loss tangent and quality factor of components comprising various exemplary dielectric materials, when operated at moderately reduced temperatures (for example, about 120 K), may be modified via application of an external magnetic field. In various exemplary embodiments, the unloaded quality factor of certain exemplary materials may be increased by more than two orders of magnitude at 4.2 K and by a factor of significantly more than 2 at 120 K via application of an 8 T external magnetic field. Accordingly, principles of the present disclosure contemplate that these effects may be desirably utilized at temperatures greater than 4.2 K and up to and including 150 K. Notably, certain high-temperature superconductors (e.g., cuprates and/or iron pnictides) may desirably be utilized in electronic systems over much of this temperature range.

Similarly, with reference now to FIGS. 4A and 4B, principles of the present disclosure contemplate that the loss tangent and quality factor of components comprising various exemplary dielectric materials, when operated at approximately room temperature (300 K), may be modified via application of an external magnetic field.

As illustrated in FIGS. 3A through 4B, it can be seen that spin excitations play a dominant role in microwave loss at cryogenic temperatures; moreover, spin excitations play a smaller role in microwave loss at room temperatures.

With reference now to FIG. 5, in various exemplary embodiments an electrical system, for example electrical system 500, may be configured with a dielectric component 520 and a magnetic field generation component 530. In an exemplary embodiment, dielectric component 520 comprises an electrical device (for example an oscillator, resonator, filter, amplifier, mixer, photonic detector, and/or the like) comprising an exemplary dielectric material as discussed hereinabove. Magnetic field generation component 530 is functionally coupled to dielectric component 520. Magnetic field generation component 530 is configured to generate a fixed and/or varying magnetic field and apply the magnetic field to dielectric component 520. Magnetic field generation component 530 may comprise one or more of a rare earth magnet, an electromagnet, an array of magnets, a solenoid, and/or any other suitable components configured to generate, modify, and/or control a magnetic field.

In exemplary embodiments wherein the magnetic field generated by magnetic field generation component 530 is static, magnetic field generation component 530 may be movable with respect to dielectric component 520 in order to vary the effective magnetic field applied to dielectric materials in dielectric component 520. In some exemplary embodiments wherein the magnetic field generated by magnetic field generation component 530 is variable, magnetic field generation component 530 may comprise various microprocessors and/or other control electronics, and/or power sources (batteries, external DC current sources, external A/C current sources, and/or the like), in order to control and/or modulate the effective magnetic field applied to dielectric materials in dielectric component 520. Moreover, any suitable methods and/or components for applying and/or varying a magnetic field to dielectric component 520 are considered to fall within the scope of principles of the present disclosure.

With reference now to FIG. 6A, an exemplary method 600 for reducing the loss tangent in an electrical device comprises: operating an electrical device having a dielectric component, wherein the operating subjects the dielectric component to electromagnetic radiation having a frequency of between about 0.2 GHz and about 120 GHz (step 610); and applying a magnetic field to the dielectric component to reduce the loss tangent in the electrical device (step 620). In some exemplary embodiments, the operating subjects the dielectric component to electromagnetic radiation having a frequency of between about 3 GHz and about 30 GHz. In certain exemplary embodiments the operating subjects the dielectric component to electromagnetic radiation having a frequency of between about 6 GHz and about 11 GHz. In certain exemplary embodiments, the applied magnetic field has a value of 0.1 Tesla or more.

Turning to FIG. 6B, an exemplary method 650 for modifying the performance of an electrical device comprises: operating the electrical device having a dielectric component, wherein the operating subjects the dielectric component to electromagnetic radiation having a frequency of at least 0.2 GHz (step 660); and applying a magnetic field to the dielectric component to modify the transfer function of the electrical device (step 670). In some exemplary embodiments, the operating subjects the dielectric component to electromagnetic radiation having a frequency of between about 3 GHz and about 30 GHz. In certain exemplary embodiments the operating subjects the dielectric component to electromagnetic radiation having a frequency of between about 6 GHz and about 11 GHz. In certain exemplary embodiments, the applied magnetic field has a value of 0.1 Tesla or more.

Principles of the present disclosure contemplate use of external magnetic fields to effectively turn a microwave device “on” (i.e., by significantly decreasing the loss tangent of the dielectric and/or modifying the Q of the device) via application of an external magnetic field. Similarly, the applied magnetic field may be reduced and/or removed to effectively turn the microwave device “off” (i.e., by significantly increasing the loss tangent of the dielectric and/or modifying the Q of the device). These exemplary operations may be selected to manipulate the performance of a device over the entire frequency range of operation, or only over a subset thereof. Additionally, the strength of an applied magnetic field may be varied and/or modulated to achieve an intermediate range of effects in the microwave device. In this manner, microwave devices may be operated under a variety of regimes and/or with a variety of transfer functions, i.e., in order to provide a type of selectivity by an external input that may be considered somewhat analogous to operation of a transistor.

While the principles of this disclosure have been shown in various embodiments, many modifications of structure, arrangements, proportions, the elements, materials and components, used in practice, which are particularly adapted for a specific environment and operating requirements may be used without departing from the principles and scope of this disclosure. These and other changes or modifications are intended to be included within the scope of the present disclosure.

The present disclosure has been described with reference to various embodiments. However, one of ordinary skill in the art appreciates that various modifications and changes can be made without departing from the scope of the present disclosure. Accordingly, the specification is to be regarded in an illustrative rather than a restrictive sense, and all such modifications are intended to be included within the scope of the present disclosure. Likewise, benefits, other advantages, and solutions to problems have been described above with regard to various embodiments. However, benefits, advantages, solutions to problems, and any element(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential feature or element.

As used herein, the terms “comprises,” “comprising,” or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Also, as used herein, the terms “coupled,” “coupling,” or any other variation thereof, are intended to cover a physical connection, an electrical connection, a magnetic connection, an optical connection, a communicative connection, a functional connection, and/or any other connection.

When a phrase similar to “at least one of A, B, or C” or “at least one of A, B, and C” is used in the claims or specification, Applicants intend the phrase to mean any of the following: (1) at least one of A; (2) at least one of B; (3) at least one of C; (4) at least one of A and at least one of B; (5) at least one of B and at least one of C; (6) at least one of A and at least one of C; or (7) at least one of A, at least one of B, and at least one of C. 

What is claimed is:
 1. A method for modifying the loss tangent in an electrical device, the method comprising: operating the electrical device having a dielectric component containing a paramagnetic additive, wherein the operating subjects the dielectric component to microwave radiation; and applying a static magnetic field to the dielectric component to modify the loss tangent in the dielectric component.
 2. The method of claim 1, wherein the static magnetic field has a strength exceeding 50 gauss.
 3. The method of claim 1, wherein the paramagnetic additive comprises at least one of a transition metal or a rare earth element.
 4. The method of claim 1, wherein the dielectric component comprises at least one of: Ni- and Zr-alloyed Ba(Zn_(1/3)Ta_(2/3))O₃, Co-alloyed Ba(Zn_(1/3)Nb_(2/3))O₃, ZrTiO₄—ZnNb₂O₆, or BaTi₄O₉—BaZn₂Ti₄O₁₁.
 5. The method of claim 1, wherein applying the static magnetic field results in modification of the spin loss properties in the dielectric component.
 6. The method of claim 1, wherein during the operating, the dielectric component is configured with a temperature lower than 300 Kelvin.
 7. The method of claim 6, wherein the loss tangent of the dielectric component is reduced by more than a factor of 2 responsive to application of the static magnetic field.
 8. The method of claim 6, wherein the loss tangent of the dielectric component is reduced by at least two orders of magnitude responsive to application of the static magnetic field.
 9. The method of claim 1, wherein the applying the static magnetic field to the dielectric component causes paramagnetic ions of the paramagnetic additive to assume a preferential spin alignment.
 10. The method of claim 1, wherein the applying the static magnetic field to the dielectric component causes paramagnetic ions of the paramagnetic additive to attain a resonant condition.
 11. The method of claim 1, wherein the paramagnetic additive comprises at least one of chromium (Cr), cobalt (Co), copper (Cu), iron (Fe), manganese (Mn), or nickel (Ni).
 12. The method of claim 1, wherein during the operating, the dielectric component is configured with a temperature of about 4.2 Kelvin.
 13. The method of claim 1, wherein the dielectric component is an insulator.
 14. The method of claim 1, wherein the dielectric component is at least one of an oxide, a nitride, or a fluoride.
 15. The method of claim 1, wherein the dielectric component is configured with a perovskite structure.
 16. A method for varying the transfer function of an electrical device, the method comprising: operating the electrical device having a dielectric component containing a paramagnetic additive, wherein the operating subjects the dielectric component to microwave radiation; applying a first static magnetic field to the dielectric component to cause the electrical device to operate according to a first transfer function; and applying a second static magnetic field to the dielectric component to cause the electrical device to operate according to a second transfer function, wherein the first static magnetic field and the second static magnetic field have a different strength.
 17. The method of claim 16, wherein the electrical device comprises at least one of a microwave filter or a microwave resonator.
 18. A method for modifying loss in a dielectric material, the method comprising: determining, for paramagnetic ions in the dielectric material, a preferential spin alignment; and applying, to the dielectric material, a static magnetic field to cause the paramagnetic ions to assume the preferential spin alignment.
 19. A method for operating a microwave device having a dielectric component containing a paramagnetic additive comprising a transition metal, the method comprising: operating, at a cryogenic temperature, the microwave device to subject the dielectric component to microwave radiation and cause a loss process to occur in the dielectric component, wherein the dominant portion of the loss process is resonant spin excitations of unpaired d-electrons of the transition metal.
 20. The method of claim 19, wherein the dielectric component is configured with a dopant concentration for the paramagnetic additive of less than or equal to 0.5%, and wherein the resonant spin excitations arise primarily within isolated transition metal atoms in the dielectric component.
 21. The method of claim 19, wherein the dielectric component is configured with a dopant concentration for the paramagnetic additive of greater than 0.5%, and wherein the resonant spin excitations arise primarily within exchange-coupled transition metal clusters in the dielectric component.
 22. The method of claim 19, wherein the dielectric component comprises Ni- and Zr-alloyed Ba(Zn_(1/3)Ta_(2/3))O₃.
 23. The method of claim 19, wherein the paramagnetic additive comprises at least one of chromium (Cr), cobalt (Co), copper (Cu), iron (Fe), manganese (Mn), or nickel (Ni). 